The mud fiend is a lurking predator formed entirely from
mud, slime and muck. Most scholars assume that the mud
fiend is a sentient force that inhabits and animates mud, as
the creatures seem indistinguishable from the wallows that
are their home. Others believe it to be a colony of
microscopic animals cooperating to create a common
defense out of the mud.
Mud fiends require decaying flesh to sustain their foul
existence and treat the bodies of their victims as fertilizer for
their homes. A mud fiend forms a body that is roughly mansized, but this form is temporary and can reform if destroyed.
There appears to be no known way to permanently destroy a
mud fiend, other than by drying out or removing the mud that
is its domain.